ISIS eyes Mecca.

ISIS has an opportunity to become an empire after the death of Abdullah.  It's plausible that an attack breaching Saudi Arabia's northern desert wall will produce the same craven disorder the Iraq attack did.  Saudi troops may flee, abandon weapons and large numbers may swap sides.  (h/t smalldeadanimals for the link to global guerillas.)  Whoever holds Mecca and Medina is the de facto guardian of the spirit of the Islamic world.

Other points at Global Guerillas:  The Saudis have indoctrinated their population with Wahhabi doctrine that tends to like ISIS and small cells of militant believers can stir up mayhem to add confusion while the ISIS warriors race up paved roads in the desert.   Every win wins more recruits and ISIS has to have increasingly spectacular attacks to keep the spotlight and survive.  More borders will be redrawn, the US could end up with soldiers defending oil fields in Saudi Arabia of all places.

Backgrounder map from Global Guerillas

"If this doesn't occur, ISIS missed the opportunity  ...    ISIS is a theocratic network of networks that is both entrepreneurial and dynamic. The Kingdom of Saudi Arabia is a theocratic hierarchy that's risk averse and inflexible. Which one wins?"

Also, we heard about the Israeli attack in Syria that killed an Iranian general but we didn't hear about a demoralizing ISIS attack two weeks ago that used insider information to kill the Saudi general in charge of the northern border.

ISIS in Mecca, no longer a black swan proposition.  The pooh-poohers should expect to be killed in ISIS land.